Our need for resources is driving development of some of the world's most remote regions. So how do we get the heavy machinery needed to explore areas where roads exist only as dotted lines on a map? You use a helicopter the size of a jumbo jet.

The Mi-26 Halo is the largest commercially-produced helicopter in the world. It was built by Soviet aerospace manufacturer Aeroflot in the 1970s from the earlier M-6 design to serve primarily in both military and civilian heavy-lift operations with a capacity twice that of other helicopters of the time. The Mi-26's cavernous cargo hold measures 3.20m wide, 3.15m high, and 15m deep—large enough to carry a pair of 10,000kg armored troop transports or up to 100 civillians, 80 combat-equipped soldiers, or 60 stretchers. Overall, the Halo measures 40m long, stands over 8m tall, and weighs 28,200 kg empty—that's just half its regular takeoff weight, which helps the chopper achieve its massive load capacity of over 20 tons. What's more, its capable of toting thes loads at speeds up to 183 mph and as far as 1,190 miles.

Getting all this machinery off the ground is no easy feat. The Mi-26 relies on a pair of Lotarev D-136 turbo-shafts, each producing in excess of 11,000HP, to spin the helicopter's staggeringly-large eight-blade propeller. At 32m in diameter, the Halo's propeller is as wide as a 737's wingspan and the first to successfully use an eight-blade design in production. Controlling this behemoth requires a crew of four—two pilots, a navigator, a flight engineer, a flight technician, and occasionally and additional cargo handler—though the pilots do get some help from the flight control's redundant autopilot, stability-augmentation, and automatic hover systems.

While the Halo was exclusive property of the USSR for years after it was built, these choppers now operate in countries around the world—at least in the 20 or so that can shell out the $11 million it costs. [Wikipedia - FAS - Military Today - Aviastar - Image: English Russia]